Accumulator diaphragm



y 1942- K. R. HERMAN 2,283,439 7 I ACCUMULATOR DIAPHRAGM Filed Dec. 21,1940 INVENTOR KENNETH R..HERMAN ATTORNEY Patented May 19, N42

ACfiUM'ULATOR DIAPHRAGM Kenneth R. Herman, Detroit, Mich, assignor toVickers Incorporated, Detroit, Mich, a corpo- I ration of MichiganApplication December 21, 1940, Serial No. 371,077

4 Claims.

This invention relates to power transmissions, particularly to those ofthe type comprising two or'more fluid pressure energy translatingdevices,

one of which may function as a pump and another as a fluid motor. 4

The invention is more particularly concerned with a flexible diaphragmused as a separator in an air-loaded accumulator of the spherical typefor use in power transmission systems of this character. In thecopending application Serial No. 309,735, filed December 18, 1939, thereis disclosed an accumulator having a flexible diaphragm formed ofoil-proof synthetic rubber and arranged to be clamped between twohemispherical halves of the accumulator proper. The diaphragm theredisclosed has been found in practice to operate satisfactorily undernormal conditions. Difiiculties have, however, been occasionallyexperienced, and his an object of the present invention to provide animproved diaphragm eliminating these dimculties. One such difiicultyencountered is that occasionally the accumulator will not release itsfull oil capacity into the working circuit. This has been found to bedue to trapping of oil within the folds of the accumulator when the sameis nearly empty, and if the center portion of the diaphragm contacts theoil outlet and is forced against the same with sufficient pressure, oilwill be trapped within the annular corrugations which are stillunfiattened against the hemispherical sides of the accumulator.

It is an object of the present invention to provide a diaphragm whichwill prevent any trapping of oil so that the oil chamber may becompletely emptied under both conditions of high or low pressure in theair chamber.

It has also been found difficult to manufacture perfect diaphragms ofthe previous type and furthermore to detect certain imperfectionstherein except as is manifested by ultimate failure in operation. Thisdimculty centers around the necessity for centrally locating a fabricreinforcement within the diaphragm itself which reinforcement isprovided for preventing the diaphragm from being "forced through thescreen over the oil outlet. Accordingly, it is another object of theinvention to provide an improved diaphragm wherein the location of thefabric reinforcement may be readily determined in a simple manner and tothus detect imperfect diaphragms before placing them in service.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing wherein a preferred form of the present invention is clearlyshown.

In the drawing:

Figure 1 is a cross section of an accumulator incorporating .a preferredform of the present invention. v

Figure 2 is a bottom view of the accumulator I diaphragm shown in Figure1.

Figure 3 is a cross section through the central portion of the diaphragmon a larger scale.

Figure 4 is a view corresponding to Figure 3 showing a method of testingthe location of the reinforcement.

The accumulator may be formed as in the aforesaid copending applicationby two generally hemispherical cups ill and 82 which are screw threadedtogether at their open ends to provide an air chamber It and an oilchamber it. The former is provided 'with a charging connection l8 whilethe latter has a screened oil connection 20.

A diaphragm 22 is clamped between the two halves and serves to separatethe air from the oil regardless of the relative volumes of fluid withinthe accumulator. For this purpose the diaphragm is provided with annularcorrugations 2t and 25 of varying depth. The central portion of thediaphragm is made significantly thicker than the remainder thereof andis provided with a fabric reinforcing disk 28.

The lower face of the diaphragm is provided with a plurality of pairs ofradial ribs which are located closely adjacent to one another to providea U-shaped groove between the ribs. These ribs preferably extend asclose as possible to the center of the diaphragm. When the diaphragm ispressed into engagement with the lower half iii, the ribs prevent theflat face of the diaphragm from contacting the walls of the oil chamberover those portions immediately adjacent to the ribs. The groove betweenthe ribs also forms a channel through which oil which might be trappedin the corrugations may be drained through the connection 20.

The reinforcement 28 is positioned beneath the upper surfaceof thediaphragm but closely adjacent thereto. In the processof manufacturingthe diaphragm, a mold cavity conforming to the shape of the finisheddiaphragm is charged with disks of raw synthetic rubber of smallerdiameter than. the finished diaphragm but of greater thickness. This hasbeen found necessary in order to cause the raw material to flow radiallyoutward to fill the mold cavity and to push any air within the cavityahead of it. The reinforcement is laid on top of the main body of rawmaterial and a thin disk of raw material placed on top of thereinforcement. If the various disks of raw material are not carefullycentered in the mold cavity, it is found that, due to the flow ofmaterial radially outward, the reinforcement is sometimes carried somedistance of! from itsdesired central position.

The positioning of the reinforcement near to but just beneath the uppersurface of the diaphragm enables the location of the reinforcement to bechecked after the diaphragm has been finished. This may be tested, asillustrated in Figure 4, by bending a portion of the diaphragm adJacentto the edge of the reinforcement in such a way as to place the uppersurface in tension. when this occurs, the edge of the reinforcementappears to protrude from the upper surface. In fact, it is possible tosee the fabric pattern through the thin film of artificial rubber whenit is thus placed in tension. In this way the location of thereinforcement may be readily checked although such reinforcement is notthe least bit visible when the diaphragm is unstressed. This latter factis due to the smooth surface of the upper half of the mold. cavitywhich, regardless of the flnal position of the reinforcement, alwaysproduces a smooth surface on the top face of the diaphragm.

It will thus be seen that the present invention provides an improveddiaphragm which will prevent the trapping of oil as the accumulatorbecomes nearly emptied of oil and also provides a ready means wherebythe accuracy of location of the central reinforcing patch may be readilychecked,

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted; all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A flexible diaphragm for separating gas and liquid in a fluidpressure accumulator comprising a sheet of flexible, impervious,rubber-like material annularly corrugated so as to flex, withoutsubstantial stretching, into either half ofsubstantially a sphere inwhich the diaphragm is diametrically positioned, said diaphragm havingaplurality of small raised ribs on its liquid contacting surface, saidribs, when the diaphragm is in contact with the walls of the liquidchamber of the accumulator, providing drainage paths extending to theliquid outlet whereby trapped liquid pockets may be fully drained whenemptying the accumulator of liquid.

2. A flexible diaphragmfor separating gas and liquid in a fluid pressureaccumulator comprising a sheet of flexible, impervious, rubber-likematerial annularly corrugated so as to flex, without substantialstretching, into either half of substantially a sphere in which thediaphragm is diametrically positioned, said diaphragm having a pluralityof small raised ribs on its liquid contacting surface and arranged inparallel sets providing channels therebetween, said ribs, when thediaphragm is in contact with the walls of the liquid chamber of theaccumulator, providing drainage paths extending to the liquid outletwhereby trapped liquid pockets may be fully drained when emptying theaccumulator of liquid.

3. A flexible diaphragm for separating gas and 1 liquid in a fluidpressure accumulator comprisin a sheet of flexible, impervious,rubber-like material annularly corrugated so as to flex, withoutsubstantial stretching, into either half of substantially a sphere inwhich the diaphragm is diametrically positioned, said diaphragm having aplurality of small raised ribson its liquid contacting surface andarranged radially from the center of the diaphragm, said ribs, when thediaphragm is in contact with the walls of the liquid chamber of theaccumulator, providing drainage paths extending to the liquid outletwhereby trapped liquid pockets may be fully drained when emptying theaccumulator of liquid.

4. A flexible diaphragm for separating gas and liquid in a fluidpressure accumulator comprising a sheet of flexible, impervious,rubber-like material having a portion overlying the liquid inlet whenthe accumulator is emptied of liquid, and means for preventing ruptureof the diaphragm by gas pressure when overlying said inlet, said meanscomprising a fabric reinforcement subject to lateral displacement withinthe diaphragm during the manufacture thereof, said reinforcement beingpositioned beneath but closely adjacent one surface of the sheet wherebythe location of the reinforcement may be visually evidenced by locallyflexing the diaphragm adjacent the edge of the reinforcement.

KENNETH R. HERMAN.

